Here's a couple of links that might help using certified IFR gps. All of which have an OBS function (like the old Lowrance did)
Radial in a flight plan: https://youtu.be/qb6k0DKWOcs
OBS mode (vs typical leg mode) https://youtu.be/tmOw0V_DZ9M (start @ 6:30 in)
Hope this helps clarify my earlier comments re: OBS mode on the old Lowrance.
ok - so now on departure from ABC fly runway heading until you intercept the 123 radial of the XYZ VOR, XYZ then as filed :-)
So let's say I could pull up my flight plan click on ABC waypoint, set OBS mode 230 F (runway heading), click on XYZ waypoint, select OBS mode 123 F
(perhaps fly draws the radial and inserts a hidden waypoint for the turn at the intercept kinda like those top of climb points etc.)
ok - time to stop thinking aloud and go shovel some snow :-)